HK1061794A1 - Prone positioning therapeutic bed - Google Patents

Abstract

A prone positioning therapeutic bed (10) comprises a base frame (16) and a patient support platform (20) rotatably mounted on the base frame (16) for rotational movement about a longitudinal rotational axis and a drive system for rotating the patient support platform on the base frame. A special head restraint apparatus (50) maintains proper patient alignment during rotation. A weight monitoring system monitors a patient's weight over time. A touch screen user interface provides a programmable therapy settings and displays statistics about past treatment. Circuitry is provided to minimise the risk that the failure of any single device or software program could endanger a patient. A "CPR" button is provided to arrest any program of therapy and return the patient support platform to a supine position. <IMAGE>

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates generally to therapeutic beds, and more particularly to an improved rotating bed capable of placing a patient in a prone position.

2. Long-felt Needs and Description of the Related Art

Patient positioning has been used in hospital beds for some time to enhance patient comfort, prevent skin breakdown, improve drainage of bodily fluids, and facilitate breathing. One of the goals of patient positioning has been maximization of ventilation to improve systematic oxygenation. Various studies have demonstrated the beneficial effects of body positioning and mobilization on impaired oxygen transport. The support of patients in a prone position can be advantageous in enhancing extension and ventilation of the dorsal aspect of the lungs.

Proning has been recognized and studied as a method for treating acute respiratory distress syndrome ("ARDS") for more than twenty-five years. Some studies indicated that approximately three quarters of patients with ARDS will respond with improved arterial oxygenation when moved from the supine to the prone position.

There are several physiological bases for patient proning. When a person lies flat in the supine position, the heart and sternum lie on top of and compress the lung volume beneath it. Moreover, the abdominal contents push upwards against the diaphragm and further compress and increase the pressures on the most dorsal lung units, where perfusion (i.e., blood flow volume reaching alveolocapillary membranes) is greatest. In an ARDS patient; ventilation in these dorsal regions is inhibited by fluid and cellular debris that settle into the most dependent lung segments. Lung edema may further increase the plural pressures in the most dependent regions. The combination of fluid accumulation with compression by the heart, sternum, and abdominal contents on the dorsal regions of the lung results in a significant ventilation-perfusion mismatch. Expressed more simply, the air entering the patient's lungs is not reaching those parts of the lungs (the dorsal regions where perfusion is greatest) that most need it.

Despite its promises, prone positioning has not been widely practised on patients because, due to the inadequacies of prior art devices, it is difficult and labor-intensive process. Logistically, moving a patient to the prone position using prior art technology requires careful planning, coordination, and teamwork to prevent complications such as inadvertent extubation and loss of invasive lines and tubes.

Prone positioning using many prior art methods and devices has caused chest tubes, invasive lines, and infusions to become kinked. Worse, the rotation of a patient from the supine to the prone position on some beds has been reported to result in inadvertent extubation and decannulation, which can have catastrophic consequences. Accordingly, there is a need for a proning device with a patient line care management system that will minimize the risk of extubation, decannulation, or kinking of patient care lines.

A prior art therapeutic bed is disclosed in WO99/62454 .

According to the invention, we provide a therapeutic bed comprising:

• a base frame; a patient support platform having a longitudinal rotational axis, the patient support platform being rotationally mounted on the base frame such that the patient support platform is capable of rotation about the longitudinal rotational axis between a supine patient and an inverted prone position; a motor operationally engaged with and operable to provide rotation of the patient support platform from the supine patient position to the prone patient position and controlled alternating rotational movement to the patient support platform about an arc of rotation;
• at least one side rail mounted on the patient support platform; one or more cushions mounted on the at least one side rail, the cushions being operable to support a patient on the patient support platform when the patient support platform is in the prone patient position wherein the at lease one side rail is moveable from a first position with the cushions extending above the patient support platform to a second position with the cushions stored beneath the patient support platform; and a strap operable to secure the one or more cushions in a position adjacent a patient lying on said patient support platform;
• characterised in that the bed comprises: a tape switch connected to said patient support platform; wherein the at least one side rail is engageable with the tape switch to provide an indication of whether the strap is sufficient tensioned.

BRIEF DESCRIPTION OF THE DRAWINGS

• Fig. 1 is a perspective view of a therapeutic bed in accordance with the present invention.
• Fig. 4 is a perspective view of a side rail of the therapeutic bed of Fig. 1.
• Fig. 16 is a side elevation view of a side rail and cooperating tape switch on a therapeutic bed in accordance with the present invention.
• Fig. 17 is a cross-sectional view of the tape switch of Fig. 16.

DETAILED DESCRIPTION

Referring to Figs. 1 and 2, a therapeutic bed 10 in accordance with the present invention preferably comprises a ground engaging chassis 12 mounted on wheels 14. A base frame 16 mounted on chassis 12 with pivot linkages 18. Rams 15, 17 housed within base frame 16 cooperate with pivot linkages 18 to form a lift system to raise and lower base frame 16 on chassis 12. A patient support platform 20 having upright end rings 22, 24 is rotatably mounted on base frame 16 with rollers 26 such that patient support platform 20 may rotate about a longitudinal axis between a supine position and a prone position, Mattress or foam padding (not shown for clarity), such as the type described in co-pending and commonly assigned application for letters patent serial number 0-9/588513 filed June 6, 2000 , entitled "MATTRESS WITH SEMI-INDEPENDENT PRESSURE RELIEVING PILLARS INCLUDING TOP AND BOTTOM PILLARS", overlays patient support platform 20.

Side support bars 28, 30 extend between end rings 22, 24. At the head of bed 10, a guide body 32 having a plurality of slots 34 for routing patient care lines (not shown) is slidably mounted on rails 36 with support rod 31. Similarly, at the foot of bed 10, a central opening 118 is provided for receiving a removable patient care line holder (not shown) having a plurality of circumferential slots for routing patient care lines.

Central opening 118 is preferably of sufficient size to allow passing of patient connected devices, such as foley bags (not shown), through the central opening 118 without disconnecting such devices from the patient. For such purposes, central opening 118 is preferably as large as possible, provided that strength and configuration requirements of the bed are maintained. More particularly, the inner diameter of central opening 118 is preferably at least eight inches, more preferably, at least about 12 inches, in diameter. The foregoing basic structure and function of bed 10 is disclosed in greater detail in international application number PCT/IE99/00049 filed June 3, 1999 .

Still referring to Fig. 1, bed 10 preferably comprises one or more folding side rails 62 pivotally mounted to patient support platform 20 to assist in securing a patient to support platform 20 before rotation into the prone position. As further described below in connection with Fig. 15, side rails 62 fold underneath platform 20 for easy access to a patient lying atop cushions 21a, 21 b, 21 c in the supine position. Bed 10 also preferably has a head rest 50 and a pair of head restraints 48, which are described in more detail below in connection with Fig. 3. Although not shown for the sake of clarity, a fan may be mounted on the patient support platform 20 near the end ring 24 at the foot of bed 10 to ventilate a patient's legs

As shown in Fig. 2, end ring 22 at the head of bed 10 is split into two sections for improved access to a patient lying on bed 10. Upper section 22a is removable from lower section 22b. Upper section 22a has a pair of shafts 40 that are inserted into vertical stabilizer tubes 38 in the closed position. Likewise, tabs 46 on upper section 22a mate with tubular opening on lower section 22b. Latches 44 secure upper section 22a to lower section 22b in the closed position. When latches 44 are unlatched, upper section 22a may be raised, pivoted about the vertical axis of one of the shafts 40, and left in an open position supported by one of the shafts 40 in corresponding stabilizer tube 38. Alternatively, upper section 22a may be removed entirely. In either case, upper section 22a may be moved out of the way for unobstructed access to the patient and manipulation of patient care lines. An alternative to a split end ring is to provide a slotted wheel 41 (Fig. 2B) having a radical slot 43 supported by a plurality of rollers 42. Patient car lines would be inserted or removed from the center of wheel 41 through slot 43. As another alternative to a split end ring, patient support platform 20 could be cantilevered from the base frame at one end of the bed, but such a configuration would be extremely heavy.

One of the key challenges in patient proning is adequately supporting the head in a manner that facilitates proper alignment of the patient's vertebrae in both the prone and supine positions, as well as the angular positions of rotation. Other challenges include minimizing the risk of skin, face, and ear abrasions and avoiding entanglement or kinking of patient care lines to the patient's head, throat, or face.

Figure 4 illustrates a preferred structure and operation of folding side rails 62. Preferably, four independently operable side rails 62 are pivotally mounted on each side of bed 10. For each side rail 62, main rail 66 is slidably mounted on shaft 80 with mounting cylinders 82. Shaft 80 has a slot 80a for receiving guides such as set screws 83 installed in holes 82a of mounting cylinders 82. Preferably, set screws 83 are not tightened against slot 80a but simply protrude into slot 80a to prevent side rail 62 from rotating with respect to shaft 80. In that regard, set screws 83 could be replaced with unthreaded pins. When set screws 83 are loosened, side rail 62 is free to slide longitudinally along shaft 80 for proper positioning with respect to the patient. When set screws 83 are tightened, side rail 62 is fixed with respect to shaft 80. Shaft 80 is rotatably mounted to side support bar 28, 30 with rail mounts 78. Pivot link 68 is hinged to main rail 66 with hinge 72, and cushion 64 is hinged to pivot link 68 with hinge 70, which has a hinge plate 70a for attaching cushion 64. Side rails 62 are thus capable of folding under patient support platform 20 as shown in Fig. 15, which is a view looking up from beneath patient support platform 20. A strap 174 with one end secured around shaft 80 may be provided to retain cushion 64 in the folder under position with mating portions of a snap respectively provided on cushion 64 and strap 174. A pair of straps 74 and an adjustable buckle 76 are provided to fasten each opposing pair of side rails 62 securely over the patient. One end strap 74 is secured to side support bar 28 with a strap connector 88, which is slidably mounted in slot 28a of side support bar 28. When strap 74 is properly secured with the appropriate tension using buckle 76, tabs 160 on strap connector 88 are sandwiched between mail rail 66 and side support bar 28, which further helps to prevent longitudinal movement of side rail 62. Side rails 62 thus serve to hold the patient securely in place as bed 10 is rotated into the prone position, and side rails 62 fold neatly out of the way for easy access to the patient in the supine position.

As illustrated in Fig. 16, instead of utilizing tension-sensitive strap connectors 88, a pressure-sensitive tape switch 234 may be installed to side support bars 28, 30 adjacent each side rail 62. Tape switch 234 is preferably of the type commonly available from the Tape Switch company. Strap 74 is attached to a crossbar 240 that spans main rails 66. When strap 74 is properly tensioned, main rails 66 depress tape switch 234, which send a signal through electrical leads 238 to the monitoring and control system indicating that side rail 62 is properly secured over the patient. Preferably, the monitoring and control system is programmed such that the patient support platform 20 is not allowed to rotate into the prone position unless all side rails 62 have been properly secured as indicated by tape switches 234. To help calibrate each tape switch 234, a pad 236 may be attached to side support bars 28, 30 below the tape switch 234 adjacent each side rail 62. Pads 236 are made of a compressible material, such as rubber, having a suitable hardness and thickness so that, as strap 74 is buckled, main rails 66 will first compress pads 236 and then depress tape switch 234 when strap 74 is buckled to the appropriate tension.

Fig. 17 illustrates a preferred embodiment of tape switch 234. A mounting bracket 242, which is preferably made of extruded aluminum, houses two conductive strips 250 and 246 that are separated at their upper and lower edges by insulator strips 248. Conductive strip 250 is a planar conductor oriented in a vertical place as shown. Conductive strip 246 is installed under a preload such that it is bowed away from conductive strip 250 in its undisturbed position. Conductive strips 250, 246 and insulator strips 248 are enclosed within a plastic shroud 244. When mail rails 66 engage tape switch 234 with sufficient pressure, conductive strip 246 is displaced to the position shown at 246a, which completes the circuit with conductive strip 250 and sends a signal through leads 238 indicating that the strap 74 is properly secured.

The therapeutic bed 10 of the present invention is useful for rotating a patient from the supine to the prone position. Preferable, proning is provided in conjunction with regular oscillating therapy or frequent movements between different angular positions to intermittently relieve pressure on the dependent surfaces of the body. For example, rotating the patient support platform 20 from a first angular position to a second angular position at least 40 degrees from the first angular position at least every two hours may be adequate to minimize the risk of skin breakdown. To provide an additional pulmonary benefit, however, it is preferred that the patient support platform 20 be rotated back and forth across an arc of at least 80 degrees while in the prone position.

Using the therapeutic bed 10 of the present invention, rotational therapy may be paused for predetermined intervals of time when the patient support platform 20 reaches the right or left angle limits, or when the platform 20 reaches the zero degree prone position. In this manner, time spent in angles greater than 40 degrees can be increased, facilitating more secretion drainage from the lungs. For example, the patient support platform 20 can be operated to periodically pause during rotation at two or three discrete angular positions, where each of said two to three discrete angular positions is at least 40 degrees from the other of said two to three discrete angular positions, and where each pause is for a period of between fifteen seconds and ten minutes. Furthermore, rotation between one of said discrete angular positions to another of said two to three angular positions might occur at least every fifteen minutes, in order to periodically alleviate pressure from the weight-bearing surfaces of the body. This will mimic the repositioning behaviour of health sleeping adults, which studies have shown reposition themselves about once every 11.6 minutes.

In operation, lateral rotational therapy in the prone position is preferably provide by rotating the patient support platform 20 no faster than 2 degrees per second in order to minimize stimulation of the vestibular system. Some patients may tolerate faster speeds. Slower speeds, such as 1 degree per second or less, may be indicated for patients suffering sever vestibular abnormalities. Accordingly, the therapeutic bed of the present invention provides an acclimate function that permits an operator to fully adjust the rotational speed of the patient support platform 20.

Prone therapy is preferably provided in conjunction with kinetic therapy using an arc of rotation of at least 80 degrees. For example, the patient support platform 20 may be rotated from the prone position to a vertical (90 degree) position, back to the opposite (-90 degree) vertical position, and so forth. Alternatively, the patient support platform 20 may be rotated from the prone position all the way to the supine position, and then the rotation is reversed for 360 degrees until the platform 20 again reaches the supine position, and so forth. For patients with acute lung injury or ARDS, kinetic therapy in the prone position is preferably provided at least about 18 out of every 24 hours.

Angle limit modifications should be made for persons with injuries or fractures on one side of the body. For example, if one of patient's two lungs is more compromised that the other, rotation should be programmed to favor drainage away from the compromised lung. If the left lung is the more compromising lung, rotation should favor the right in order to place the "right lung" down. Preferably, the patient support platform 20 is paused at the right angle limit to maintain optimal oxygenation. Such therapy should be continued until the unilateral problem begins to resolve itself, at which point the patient support platform 20 can begin to be turned to the left side. Thereafter, the patient can be gradually acclimated to bilateral rotation by gradually increasing the left angle limits and left angle pause time every 2-4 hours until they match those given on the right. Also, patients with vestibular dysfunctions may be acclimated to kinetic therapy by gradually increasing the arc of oscillation from 0 degrees to preset angle of oscillation.

Also, kinetic therapy may be provided in conjunction with both the prone and supine positions. For example, a patient may be provided kinetic therapy in the supine position for a first interval of time (preferably for 1-6 hours), followed by prone therapy in the prone position for a second interval of time (again, preferably from 1-6 hours), and then returned to the supine position for further kinetic therapy. Such kinetic therapy may be punctuated by periods of static rest in the supine or prone positions.

A number of criteria may indicate that a course of kinetic therapy has accomplished its mission and may be discontinued. If the patient's perfusion to ventilation ratio rises above 250 for 24 hours and shows an upwards trend, if the patient is extubated due to improvement, or if the patient becomes mobile or can sit up in a chair more three times a day for at least an hour each time, kinetic therapy may be discontinued.

Although the foregoing specific details describe a preferred embodiment of this invention, persons reasonably skilled in the art will recognize that various changes may be made in the details of the method and apparatus of this invention without departing from the scope of the invention as defined in the appended claims. Therefore, it should be understood that this invention is not to be limited to the specific details shown and described herein.

Claims (9)

1. A therapeutic bed (10) comprising:

   a base frame (16);

   a patient support platform (20) having a longitudinal rotational axis, the patient support platform (20) being rotationally mounted on the base frame (16) such that the patient support platform (20) is capable of rotation about the longitudinal rotational axis between a supine patient position and an inverted prone position;

   a motor (322) operationally engaged with and operable to provide rotation of the patient support platform (20) from the supine patient position to the prone patient position and controlled alternating rotational movement to the patient support platform (20) about an arc of rotation;

   at least one side rail (62) mounted on the patient support platform (20);

   one or more cushions (64) mounted on the at least one side rail, the cushions being operable to support a patient on the patient support platform (20) when the patient support platform (20) is in the prone patient position, wherein the at least one side rail is moveable from a first position with the cushions (64) extending above the patient support platform (20) to a second position with the cushions (64) stored beneath the patient support platform (20); and

   a strap (74) operable to secure the one or more cushions (64) in a position adjacent a patient lying on said patient support platform (20);

   characterised in that the bed comprises:-

   a tape switch (234) connected to said patient support platform (20); wherein the at least one side rail (62) is engageable with the tape switch (234) to provide an indication of whether the strap (74) is sufficiently tensioned.
2. The therapeutic bed (10) of Claim 1 wherein the cushions (64) are pivotally mounted on the side rail (62).
3. The therapeutic bed (10) of Claim 1 of 2 wherein the at least one side rail (62) comprises a first section pivotally attached to a side of the patient support platform (20), wherein the first section extends upwardly from and substantially perpendicular to the patient support platform (20) when the side rail (62) is in the first position, and underneath and substantially parallel to the patient support platform (20) when the side rail (62) is in the second position.
4. The therapeutic bed (10) of Claim 3, wherein the side rail (62) further comprises a second section pivotally connected to the first section, the second section extending substantially perpendicularly from the first section and substantially parallel to the patient support platform (20) when the side rail (62) is in the first position.
5. The therapeutic bed (10) of Claim 4, wherein the cushions (64) are mounted on a hinge plate pivotally mounted to the side rail (62), so that the one or more cushions (64) are operable to be folded inwardly toward the first section when the side rail (62) is in the second position.
6. The therapeutic bed (10) of Claim 5, further comprising a strap operable to retain the one or more cushions (64) mounted on the hinge plate in the inwardly folded position.
7. The therapeutic bed (10) of any one of Claims 1-5, further comprising:

   a strap operable (74) to secure the one or more cushions (64) in a position adjacent a patient lying on said patient support platform (20);

   and a strap connector (88) connected to the strap (74), the strap connector (88) providing an indication of whether the strap (74) is sufficiently tensioned.
8. The therapeutic bed (10) of any one of the preceding Claims, further comprising a control system operative to prevent rotation of the patient support platform (20) into the prone position unless the at least one or more cushions (64) are properly secured over the patient.
9. The therapeutic bed (10) of any one of the preceding Claims, further comprising a plurality of spaced-apart complementary pairs of side rails (62) pivotally mounted on opposed sides of the patient support platform (20).